1. Field of Invention
The present invention is related to mobile phones and in particular power saving for mobile phones comprising wideband code division multiple access.
2. Description of Related Art
WCDMA (Wideband Code Division Multiple Access) has become a third generation standard for mobile communications. The WCDMA replaces the GSM (Global System for Mobile Communications) a second generation standard, which is oriented to voice communications with limited data capability. The demand by users for not only voice communications but also Web browsing, downloading E-mail, and sending pictures has placed a demand for higher data rate capability. The WCDMA standard provides a spectrum with a 5 MHz carrier, which provides approximately a fifty times higher data rate than the second generation GSM technology. Along with the higher data rate capability come the need to use more power and in turn the need to have power savings to moderate the demand on the battery life of a mobile or cellular phone.
There are numerous power saving techniques that have been developed for first and second generation mobile phones. In U.S. Pat. No. 6,944,210 B1 (Michel et al.) a method is directed to receiving or transmitting messages wherein the use of spreading codes for CDMA signals provides for power saving measures. U.S. Pat. No. 6,741,836 B2 (Lee et al.) is directed to a dual mode Bluetooth/wireless mobile unit wherein a sleep mode a wakeup time is rescheduled to synchronize with any upcoming idle mode wireless wakeup time that will precede the Bluetooth wakeup time. U.S. Pat. No. 6,690,652 B1 (Sadri) is directed to a WCDMA system which includes a base station transmitter and a pilot channel that transmits control signals between the base station and the mobile station.
In U.S. Pat. No. 6,639,905 B1 (Muller et al.) a transmitter is directed to controlling at least one receiver by intermittently transmitting groups of messages and increasing the efficiency of transmitted control messages without markedly increasing power consumption of transceivers in the radio frequency network. U.S. Pat. No. 6,526,295 B1 (Shull) is directed to a power saving method comprising the delay of the turning on of a local oscillator in a mobile phone while the processor of the mobile phone sorts through a previously received neighbor list and includes a method for generating compensation factors for use in power savings. U.S. Pat. No. 6,356,595 (Czaja et al.) is directed to a method that affords low error rate and allows for improved power conservation by a mobile station. U.S. Pat. No. 6,356,538 B1 (Li) is directed to a system for operating a wireless communications device in a manner that significantly reduces power consumption of the device.
In U.S. Pat. No. 6,219,564 (Grayson et al.) a digital mobile communication station is directed to a high frequency time base circuit that shuts down for a predetermined period for power saving purposes. U.S. Pat. No. 6,125,260 (Wiedeman et al.) is directed to a radio frequency map that can be used to reallocate frequency channels of operation and resulting in power savings in a mobile phone while maintaining a suitable signal-to-noise ratio. U.S. Pat. No. 6,041,241 (Willey) is directed to an apparatus and method for balancing power savings and call setup time for a wireless communications device. U.S. Pat. No. 5,983,116 (Nash et al.) is directed to a radio telephone having an analog key signal output for power conservation. U.S. Pat. No. 5,905,943 (Wiedman et al) is directed to the use of a radio frequency map to reallocate frequency channels resulting power savings in a mobile phone. In U.S. Pat. No. 5,890,005 (Lindholm) a method is directed to reducing power consumption in an electronic system such as a wireless or cellular phone. U.S. Pat. No. 5,752,201 (Kivari) is directed to a cellular communication device that includes a controller which places the user terminal in a powered down state for a period of time depending upon the number of filler messages.
In U.S. Pat. No. 5,715,278 (Croft et al.) a method is directed to an apparatus for reducing standby power in a mobile phone while simultaneously increasing the probability of receiving the intended message. U.S. Pat. No. 5,701,329 (Croft et al.) is directed to a power saving standby mode that can be used in mobile radio stations operating in current networks and improving the intended message reception. In U.S. Pat. No. 5,570,369 (Jokinen) a method is directed to reducing power consumption in a mobile phone system wherein a broadcasted message is reconstructed from a partial signal from a base station. U.S. Pat. No. 5,568,513 (Croft et al.) is directed to a power saving standby mode that can be used in mobile radio stations using a CRC check to determine when to be on the power saving mode. U.S. Pat. No. 5,291,542 (Kivari et al.) is directed to a circuit arrangement for a mobile phone comprising a microprocessor that is responsive to a clock signal, which leads to reduced power consumption.
In FIG. 1 is shown a block diagram of a WCDMA device of prior art. An RF unit 10 couples signals to and from a modem unit 11. A search function 12 is contained within the modem unit 11 to search the spread of an incoming base band data over approximately a 5 MHz band. A host processor 13 sets up and controls the modem and RF units. Data, such as Internet, text and pictures, received by the modem 11 is coupled to the host computer 13 for display on a screen of a mobile phone 14. Data, such as internet text and pictures, generated by the mobile phone 14 are coupled to the modem for transmission by the RF unit. A power management scheme is needed for the mobile phone 14 to allow the reception of signals while at the same time preserving battery power life. The modem 11 amongst other features provide a heavy drain of power from the batteries of the mobile phone.